CN108886124B - Separator for liquid lead-acid battery - Google Patents
Separator for liquid lead-acid battery Download PDFInfo
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- CN108886124B CN108886124B CN201780020347.4A CN201780020347A CN108886124B CN 108886124 B CN108886124 B CN 108886124B CN 201780020347 A CN201780020347 A CN 201780020347A CN 108886124 B CN108886124 B CN 108886124B
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- China
- Prior art keywords
- separator
- microporous film
- microporous
- microporous membrane
- acid battery
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- 239000002253 acid Substances 0.000 title claims abstract description 47
- 239000007788 liquid Substances 0.000 title claims abstract description 39
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 120
- 238000000034 method Methods 0.000 claims abstract description 59
- 239000000843 powder Substances 0.000 claims abstract description 56
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 48
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 46
- 239000012982 microporous membrane Substances 0.000 claims abstract description 33
- 229910052736 halogen Inorganic materials 0.000 claims abstract description 25
- 239000002585 base Substances 0.000 claims abstract description 22
- 238000004993 emission spectroscopy Methods 0.000 claims abstract description 22
- 150000002367 halogens Chemical class 0.000 claims abstract description 22
- 238000005406 washing Methods 0.000 claims abstract description 22
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 21
- 150000001340 alkali metals Chemical class 0.000 claims abstract description 21
- 229910002029 synthetic silica gel Inorganic materials 0.000 claims abstract description 20
- 230000005484 gravity Effects 0.000 claims abstract description 18
- 238000004611 spectroscopical analysis Methods 0.000 claims abstract description 13
- 238000001914 filtration Methods 0.000 claims abstract description 8
- 238000004062 sedimentation Methods 0.000 claims abstract description 8
- 229910052910 alkali metal silicate Inorganic materials 0.000 claims abstract description 5
- 150000007522 mineralic acids Chemical class 0.000 claims abstract description 4
- 239000011148 porous material Substances 0.000 claims description 36
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 33
- 229910052753 mercury Inorganic materials 0.000 claims description 33
- 229920005672 polyolefin resin Polymers 0.000 claims description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- 150000003839 salts Chemical class 0.000 claims description 20
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 12
- 239000003673 groundwater Substances 0.000 claims description 6
- 239000011780 sodium chloride Substances 0.000 claims description 6
- 229910052801 chlorine Inorganic materials 0.000 abstract description 11
- 229910052794 bromium Inorganic materials 0.000 abstract description 10
- 229910052792 caesium Inorganic materials 0.000 abstract description 10
- 229910052731 fluorine Inorganic materials 0.000 abstract description 10
- 229910052740 iodine Inorganic materials 0.000 abstract description 10
- 229910052744 lithium Inorganic materials 0.000 abstract description 10
- 229910052700 potassium Inorganic materials 0.000 abstract description 10
- 229910052701 rubidium Inorganic materials 0.000 abstract description 10
- 229910052708 sodium Inorganic materials 0.000 abstract description 10
- 239000007864 aqueous solution Substances 0.000 abstract description 4
- 239000004014 plasticizer Substances 0.000 description 30
- 239000000460 chlorine Substances 0.000 description 25
- 239000004094 surface-active agent Substances 0.000 description 25
- 239000000203 mixture Substances 0.000 description 24
- 239000002994 raw material Substances 0.000 description 23
- -1 polyethylene Polymers 0.000 description 20
- 238000004519 manufacturing process Methods 0.000 description 19
- 239000002480 mineral oil Substances 0.000 description 19
- 235000010446 mineral oil Nutrition 0.000 description 19
- 230000000052 comparative effect Effects 0.000 description 16
- 239000012188 paraffin wax Substances 0.000 description 15
- 239000007787 solid Substances 0.000 description 15
- 239000000463 material Substances 0.000 description 14
- 239000003792 electrolyte Substances 0.000 description 13
- 238000002156 mixing Methods 0.000 description 13
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 13
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 11
- 239000006227 byproduct Substances 0.000 description 11
- 230000006872 improvement Effects 0.000 description 11
- 229910052938 sodium sulfate Inorganic materials 0.000 description 11
- 235000011152 sodium sulphate Nutrition 0.000 description 11
- 238000001556 precipitation Methods 0.000 description 10
- 239000008151 electrolyte solution Substances 0.000 description 9
- 239000011734 sodium Substances 0.000 description 9
- 238000002844 melting Methods 0.000 description 8
- 230000008018 melting Effects 0.000 description 8
- 229920013716 polyethylene resin Polymers 0.000 description 7
- 238000004438 BET method Methods 0.000 description 6
- 239000003795 chemical substances by application Substances 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 238000000465 moulding Methods 0.000 description 6
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 229920005989 resin Polymers 0.000 description 5
- 239000011347 resin Substances 0.000 description 5
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 description 5
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 4
- 239000004698 Polyethylene Substances 0.000 description 4
- 239000000654 additive Substances 0.000 description 4
- 229920000573 polyethylene Polymers 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 229910001413 alkali metal ion Inorganic materials 0.000 description 3
- 239000003963 antioxidant agent Substances 0.000 description 3
- 230000003078 antioxidant effect Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000004898 kneading Methods 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 150000003973 alkyl amines Chemical class 0.000 description 2
- 239000003945 anionic surfactant Substances 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 239000003093 cationic surfactant Substances 0.000 description 2
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 2
- 210000001787 dendrite Anatomy 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- YRIUSKIDOIARQF-UHFFFAOYSA-N dodecyl benzenesulfonate Chemical class CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 YRIUSKIDOIARQF-UHFFFAOYSA-N 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- 239000000284 extract Substances 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- BKIMMITUMNQMOS-UHFFFAOYSA-N nonane Chemical compound CCCCCCCCC BKIMMITUMNQMOS-UHFFFAOYSA-N 0.000 description 2
- 239000002736 nonionic surfactant Substances 0.000 description 2
- GLDOVTGHNKAZLK-UHFFFAOYSA-N octadecan-1-ol Chemical compound CCCCCCCCCCCCCCCCCCO GLDOVTGHNKAZLK-UHFFFAOYSA-N 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229930195734 saturated hydrocarbon Natural products 0.000 description 2
- 125000005372 silanol group Chemical group 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- MQIUGAXCHLFZKX-UHFFFAOYSA-N Di-n-octyl phthalate Natural products CCCCCCCCOC(=O)C1=CC=CC=C1C(=O)OCCCCCCCC MQIUGAXCHLFZKX-UHFFFAOYSA-N 0.000 description 1
- 229910000978 Pb alloy Inorganic materials 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000004931 aggregating effect Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000005215 alkyl ethers Chemical class 0.000 description 1
- 229940045714 alkyl sulfonate alkylating agent Drugs 0.000 description 1
- 150000008052 alkyl sulfonates Chemical class 0.000 description 1
- 239000003242 anti bacterial agent Substances 0.000 description 1
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 1
- 210000004027 cell Anatomy 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical class OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000000855 fungicidal effect Effects 0.000 description 1
- 239000000417 fungicide Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- PIJPYDMVFNTHIP-UHFFFAOYSA-L lead sulfate Chemical compound [PbH4+2].[O-]S([O-])(=O)=O PIJPYDMVFNTHIP-UHFFFAOYSA-L 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 239000006224 matting agent Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- GOQYKNQRPGWPLP-UHFFFAOYSA-N n-heptadecyl alcohol Natural products CCCCCCCCCCCCCCCCCO GOQYKNQRPGWPLP-UHFFFAOYSA-N 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920001083 polybutene Polymers 0.000 description 1
- 229920000306 polymethylpentene Polymers 0.000 description 1
- 239000011116 polymethylpentene Substances 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000011342 resin composition Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 239000006097 ultraviolet radiation absorber Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
- H01M50/491—Porosity
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Cell Separators (AREA)
- Secondary Cells (AREA)
Abstract
A separator for a liquid lead-acid battery, comprising a microporous membrane containing 40% by weight or more of a fine silica powder, which is a synthetic amorphous silica produced by the following sedimentation method: after an alkali silicate aqueous solution is reacted with an inorganic acid to precipitate synthetic amorphous silica, the purity is adjusted by filtration and washing; characterized in that the concentration (ICP emission spectroscopy) of alkali metal components (Li, Na, K, Rb, Cs) when the microporous membrane (10 cm. times.10 cm. times.2 sheets) was immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ and left for 24 hours was 5mg/100cm2The sheet thickness was not more than (converted to 0.2mm of the base thickness of the microporous membrane) and the concentration of the halogen components (F, Cl, Br, I) (ICP emission spectroscopic analysis) was 0.4mg/100cm2(base thickness of microporous membrane is 0.2 mm) or less.
Description
Technical Field
The present invention relates to a separator (separator) for a liquid lead-acid battery, which is used not in a so-called sealed lead-acid battery (also referred to as a valve regulated lead-acid battery) in which an electrolyte is not fluidized and which is maintenance-free, but in a so-called liquid lead-acid battery (also referred to as an exhaust lead-acid battery or an open lead-acid battery) including an electrolyte having fluidity, which is a conventional method.
Background
Conventionally, a microporous film separator called a polyethylene separator, which generally contains 20 to 60 wt% of a polyolefin resin (usually, ultra-high molecular weight polyethylene) having a weight average molecular weight of 50 ten thousand or more and has a specific surface area of 50m, has been used as a separator for a liquid lead-acid battery240 to 80 wt% of inorganic powder (usually fine silica powder) per g, 0 to 30 wt% of plasticizer (usually mineral oil) also used as a pore-forming agent, 0 to 10 wt% of surfactant (solid component), and 0 to 5 wt% of additives (antioxidant, weather resistant agent, etc.).
The microporous film separator is generally a sheet having a base thickness of about 0.1 to 0.3mm, an average pore diameter (mercury intrusion method) of about 0.01 to 0.5 μm, and a porosity (mercury intrusion method) of about 50 to 90 vol%, which is obtained by: the raw material composition obtained by mixing the polyolefin resin, the inorganic powder, the plasticizer (slightly more than the separator composition), the surfactant and the additive is extruded into a sheet form while heating, melting and kneading, and is roll-formed into a predetermined thickness, and then the plasticizer is completely or partially removed.
The inorganic powder has the following functions: adsorbing the loaded plasticizer when heating, melting and mixing the raw material composition; manufacturing the microporous structure (dense and complex pore structure and high porosity) of the microporous film; resists sheet shrinkage that occurs when plasticizers are removed during the manufacture of microporous films, and maintains dimensional stability; the microporous film is resistant to sheet shrinkage even during a heat treatment such as a drying step (moisture removal step) performed before use in battery assembly, and dimensional stability is maintained; improving the electrolyte absorbency of the microporous membrane; improving the electrolyte wettability of the microporous film; improve the electrolyte retention of the microporous film, and the like.
Therefore, as the inorganic powder, a fine silica powder is generally used, and in particular, synthetic amorphous silica produced by a sedimentation method by a wet method among dry or wet production methods is used from the viewpoint of a large specific surface area, a large oil absorption, a large number of hydrophilic groups (silanol groups), and the like.
On the other hand, in the in-vehicle use of lead storage batteries, lead storage batteries mounted on idling stop trains are increasingly required to have high charge acceptance because the amount of discharge increases. In order to improve the charge acceptance of lead-acid batteries, it is known that the presence of a large amount of alkali metal (Li, Na, K, Rb, Cs) ions in the electrolyte hinders the improvement of the charge acceptance (patent document 1).
It is also known that, in a lead-acid battery, when impurities of halogens (F, Cl, Br, and I) are mixed in a large amount, a plate grid or an electrode post made of lead or a lead alloy is corroded, which may cause deterioration of battery life performance (patent document 2).
The synthetic amorphous silica produced by the above-mentioned precipitation method is obtained by the following method: reacting an alkali silicate (sodium silicate) aqueous solution with an inorganic acid (sulfuric acid) under neutral or alkaline conditions to precipitate amorphous silica; the amorphous silica produced contains salts such as sodium sulfate as a by-product, and is subjected to a treatment of removing the salts by filtration and washing in a subsequent step (a treatment for improving the purity).
Documents of the prior art
Patent document
Patent document 1: international publication No. 2014/128803
Patent document 2: japanese patent laid-open No. 2005-251394
Disclosure of Invention
Problems to be solved by the invention
However, since the removal treatment of salts is not complete in the amorphous silica production process, the amorphous silica produced usually contains a small amount of sodium sulfate as a by-product. Therefore, the microporous film produced using the fine silica powder contains a small amount of sodium sulfate, and when used as a separator for a lead-acid battery, Na ions are eluted in an electrolyte as the battery is used, and when the amount of eluted Na ions is large, the sodium sulfate can become a factor that hinders improvement of charge acceptance.
In addition, when the salt removal treatment in the amorphous silica production step is performed by water washing, the water used for the water washing may cause the Cl component as a halogen to be mixed. That is, tap water (containing residual chlorine) may be used, and groundwater containing salt (sodium chloride) may be used. Therefore, the microporous film produced using the silica fine powder subjected to the water washing treatment with water also contains a trace amount of Cl component, and when used as a separator for a lead storage battery, Cl ions are eluted in an electrolyte as the battery is used, and when the amount of elution is large, corrosion of a plate grid or an electrode post is promoted, which may cause deterioration of the life performance of the battery.
In view of the above-described conventional problems, an object of the present invention is to provide a separator for a liquid lead-acid battery, which is a separator for a liquid lead-acid battery comprising a microporous film produced using a fine silica powder as a main raw material, the fine silica powder being a synthetic amorphous silica produced by a sedimentation method, and which can reduce the amount of alkali metal ions and halogen ions eluted from the separator into an electrolyte even when the battery using the separator is used, and which can prevent the improvement of charge acceptance and can prevent the reduction of battery life performance.
Means for solving the problems
In order to achieve the above object, as described in claim 1, the separator for a liquid lead-acid battery of the present invention is a separator for a liquid lead-acid battery comprising a microporous membrane containing 40% by weight or more of a fine silica powder which is a synthetic amorphous silica produced by the following sedimentation method: reacting an aqueous alkali silicate solution with an inorganic acid to precipitate synthetic amorphous silica, and then adjusting the purity by filtration and washing; characterized in that the concentration (ICP emission spectroscopy) of alkali metal components (Li, Na, K, Rb, Cs) when the microporous membrane (10 cm. times.10 cm. times.2 sheets) was immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ and left for 24 hours was 5mg/100cm2The sheet thickness was 0.2mm or less (base thickness of microporous membrane) and the concentration of halogen components (F, Cl, Br, I) (ICP emission spectroscopic analysis) was 0.4mg/100cm2(base thickness of microporous membrane is 0.2 mm) or less.
The separator for a liquid lead-acid battery according to claim 2 is the separator for a liquid lead-acid battery according to claim 1, and is characterized in that the filtration and washing are performed using ion-exchanged water or groundwater containing no salt (sodium chloride).
The separator for a liquid lead-acid battery according to claim 3 is the separator for a liquid lead-acid battery according to claim 1 or 2, wherein the microporous film is a microporous film mainly composed of the fine silica powder and a polyolefin resin.
The separator for a liquid lead-acid battery according to claim 4 is the separator for a liquid lead-acid battery according to claim 3, wherein the microporous film has a base thickness of 0.1 to 0.3mm, an average pore diameter (mercury intrusion method) of 0.01 to 0.5 μm, and a porosity (mercury intrusion method) of 50 to 90 vol%.
Effects of the invention
According to the present invention, a separator for a lead storage battery can be provided which comprises a microporous film produced using a fine silica powder produced by sedimentation as a main raw material, wherein the fine silica powder is a synthetic amorphous silica, and wherein, even when the battery using the separator is used, the amount of alkali metal ions and the amount of halogen ions eluted from the separator into an electrolytic solution can be reduced, the improvement of charge acceptance can be prevented less easily, and the reduction of battery life performance can be prevented less easily.
Detailed Description
The separator for a liquid lead-acid battery of the present invention is conditioned by: the concentration of alkali metal components (Li, Na, K, Rb, Cs) when a microporous membrane (10 cm. times.10 cm. times.2 sheets) was immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ for 24 hours (ICP emission spectroscopy) was 5mg/100cm2The sheet thickness was 0.2mm or less (base thickness of microporous membrane) and the concentration of halogen components (F, Cl, Br, I) (ICP emission spectroscopic analysis) was 0.4mg/100cm2A microporous membrane comprising 40% by weight or more of a fine silica powder (hereinafter, may be simply referred to as "the fine silica powder") in terms of a sheet (0.2 mm equivalent to the base thickness of the microporous membrane), the fine silica powder being a synthetic amorphous silica produced by the following precipitation method: after the amorphous silica is synthesized by precipitation by reacting an aqueous alkali silicate solution with a mineral acid, the purity is adjusted by filtration and washing with water (the purity of the amorphous silica is improved by removing salts as by-products).
The microporous membrane (10 cm. times.10 cm. times.2 sheets) was immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃The concentration of alkali metal components (Li, Na, K, Rb, Cs) when the substrate was left for 24 hours (ICP emission spectroscopy) was 5mg/100cm2The amount of alkali metal ions eluted from the separator into the electrolytic solution can be suppressed in the liquid lead-acid battery using the separator for a liquid lead-acid battery of the present invention, and therefore, the improvement of the charge acceptance is not easily hindered. Therefore, the concentration of the alkali metal component (ICP emission spectroscopy) when the microporous membrane (10 cm. times.10 cm. times.2 sheets) is immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ and left for 24 hours is more preferably 4mg/100cm2The number of the sheets is below.
The concentration of halogen components (F, Cl, Br, I) (ICP emission spectroscopy) when the microporous membrane (10 cm. times.10 cm. times.2 sheets) was immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ for 24 hours was 0.4mg/100cm2The liquid lead-acid battery using the separator for a liquid lead-acid battery of the present invention can suppress the amount of halogen ions eluted from the separator into the electrolytic solution, and therefore, deterioration of the battery life performance due to promotion of corrosion of the plate grid or the electrode post is less likely to occur. Therefore, the concentration of the halogen component (ICP emission spectroscopy) when the microporous membrane (10 cm. times.10 cm. times.2 sheets) is immersed in 126g of sulfuric acid having a specific gravity of 1.26 at 50 ℃ and left for 24 hours is more preferably 0.2mg/100cm2Less than one sheet, more preferably 0.1mg/100cm2The number of the sheets is below.
The microporous film is preferably a microporous film mainly composed of the fine silica powder and a polyolefin resin, and the microporous film is preferably a microporous film having a base thickness of 0.1 to 0.3mm, an average pore diameter (mercury intrusion method) of 0.01 to 0.5 μm, and a porosity (mercury intrusion method) of 50 to 90 vol%. The base thickness (base thickness) is a term used to distinguish it from the total thickness including rib-like protrusions when the microporous film has the rib-like protrusions, for example, and refers to the film thickness excluding the height of the rib-like protrusions (when the rib-like protrusions are not provided).
As described above, the fine silica powder has: adsorbing the loaded plasticizer when heating, melting and mixing the raw material composition; manufacture ofThe microporous structure of microporous films (dense and complex pore structure and high porosity); resists sheet shrinkage that occurs when plasticizers are removed during the manufacture of microporous films, and maintains dimensional stability; the microporous film is resistant to sheet shrinkage even during a heat treatment such as a drying step (moisture removal step) performed before use in battery assembly, and dimensional stability is maintained; improving the electrolyte absorbency of the microporous membrane; improving the electrolyte wettability of the microporous film; since the microporous membrane has an effect of improving the retention of an electrolyte solution, it is necessary to produce synthetic amorphous silica by a precipitation method using a wet method in a dry or wet method production method from the viewpoint of a large specific surface area, a large oil absorption amount, a large amount of hydrophilic groups (silanol groups), and the like, but the synthetic amorphous silica produced by the precipitation method using a wet method contains salts such as sodium sulfate as a by-product, and the salts are not completely removed by a treatment such as filtration and washing in a subsequent step. Therefore, in the present invention, as the fine silica powder, a synthetic amorphous silica produced by a wet precipitation method is used, in which the contents of alkali metal components (Li, Na, K, Rb, Cs) and halogen components (F, Cl, Br, I) are reduced to the following levels: the concentration of the alkali metal component (ICP emission spectroscopy) when the microporous membrane (10 cm. times.10 cm. times.2 sheets) thus obtained was immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ and left for 24 hours was 5mg/100cm2Not more than one sheet and the concentration of halogen component (ICP emission spectroscopic analysis) was 0.4mg/100cm2The number of the sheets is below. In the production process of the amorphous silica of the present invention, the water washing treatment (treatment for removing salts as by-products) is preferably performed using ion-exchanged water or groundwater containing no salt (sodium chloride). In the present application, the groundwater containing no salt (sodium chloride) means groundwater having a salt (sodium chloride) concentration of 300ppm or less.
The microporous film preferably has a base thickness of 0.1 to 0.3mm, and if it exceeds 0.3mm, the resistance is deteriorated, and if it is less than 0.1mm, it becomes difficult to maintain good short-circuit resistance (short-circuit here refers to both a penetration short-circuit called dendrite short and a normal short-circuit caused by opening or cracking of pores due to a weak portion of a local substrate, high pressure from a convex portion of a plate, impact, puncture, oxidation loss due to oxidation force from a plate, and the like).
The porosity (mercury intrusion method) of the microporous film is preferably 50% by volume or more, and by 50% by volume or more, the internal resistance (resistance) can be suppressed to be low as a separator for a liquid lead-acid battery, which contributes to high performance of the liquid lead-acid battery. Therefore, the porosity (mercury intrusion method) of the microporous film is more preferably 60 to 90 vol%, and still more preferably 70 to 90 vol%.
The method for obtaining the microporous film preferably comprises the following steps: the method comprises melt-kneading a raw material composition mainly comprising a polyolefin resin, the fine silica powder and a plasticizer, and removing a part or all of the plasticizer after film formation. This results in a film having numerous interconnected pores with a complex path that is uniformly, finely, and complicatedly entangled throughout the film. An example of a specific production method is shown below. First, a raw material obtained by adding various additives (a surfactant, an antioxidant, a weather resistant agent, and the like) to predetermined amounts of a polyolefin resin, the fine silica powder, and a plasticizer as needed is stirred and mixed by a mixer such as a henschel mixer or an レーディゲ mixer to obtain a raw material mixture. Next, the mixture was fed into a twin-screw extruder equipped with a T-die at the tip, and extruded into a sheet shape while being heated, melted and kneaded, and passed between a pair of forming rolls, one of which was engraved with a predetermined groove, to obtain a film-like material in which ribs having a predetermined shape were integrally formed on one surface of a flat plate-like sheet. Next, the film-like material is immersed in an appropriate solvent (for example, n-hexane), and a predetermined amount of mineral oil is extracted and removed, followed by drying, to obtain a target microporous film. The raw material composition is a composition composed of all raw materials fed in the melt-kneading step, and the meaning of the raw material composition is "all raw materials (composition)", and the meaning of the raw material mixture and the melt-kneaded product is not particularly specified.
The microporous film preferably contains a polyolefin resin, the fine silica powder and a plasticizer in a total amount of 90 wt% or more, a polyolefin resin in an amount of 20 to 60 wt%, a fine silica powder in an amount of 40 to 80 wt%, a plasticizer in an amount of 0 to 30 wt%, and a surfactant in an amount of 0 to 8 wt%. If the content of the polyolefin-based resin is less than 20% by weight or the content of the fine silica powder exceeds 80% by weight, the mechanical strength, oxidation resistance and sealing property of the microporous film by the polyolefin-based resin are not sufficiently ensured, and if the content of the polyolefin-based resin exceeds 60% by weight or the content of the fine silica powder is less than 40% by weight, it becomes difficult to ensure a large porosity and a fine and complicated pore structure of the microporous film, and the favorable electrical resistance characteristics of the microporous film separator cannot be maintained.
As the polyolefin-based resin, a homopolymer or a copolymer of polyethylene, polypropylene, polybutene, polymethylpentene, or the like, and a mixture thereof can be used. Among them, polyethylene is preferred as a main component in view of moldability and economy. Polyethylene has a lower melt molding temperature than polypropylene, and is excellent in productivity and production cost is suppressed. The polyolefin resin has a weight average molecular weight of 50 ten thousand or more, and thus can ensure the mechanical strength of a microporous film containing a large amount of fine silica powder. Therefore, the weight average molecular weight of the polyolefin resin is more preferably 100 ten thousand or more, and still more preferably 150 ten thousand or more. The polyolefin resin and the fine silica powder are also excellent in miscibility, and the fine silica powder is chemically stable and highly safe while maintaining strength as an adhesive functional material for bonding the skeleton of the fine silica powder in the microporous film.
As the fine silica powder, fine silica powder having a fine particle diameter and having a pore structure inside and on the surface thereof can be used. In inorganic powders, dioxygenThe silica has a wide selection range of various powder characteristics such as particle diameter and specific surface area, and is easily available at a relatively low cost with less impurities. When the specific surface area of the fine silica powder is 100m2The pore structure of the microporous film is preferably made finer (densified) and more complicated to improve short-circuit resistance and to improve electrolyte retaining force of the microporous film, and the hydrophilicity of the microporous film is preferably improved by having a large number of hydrophilic groups (-OH) on the surface of the powder. Therefore, the specific surface area of the fine silica powder is more preferably 150m2More than g. The specific surface area of the fine silica powder is preferably 400m2The ratio of the carbon atoms to the carbon atoms is less than g. The specific surface area of the fine silica powder is more than 400m2In the case of the fine particles/g, the surface activity of the particles is high, and the aggregating power is increased, so that it becomes difficult to uniformly disperse the fine silica powder in the microporous film, which is not preferable.
As the plasticizer, a material that can be used as a plasticizer for the polyolefin resin is preferably selected, and various organic liquids that are compatible with the polyolefin resin and can be easily extracted with various solvents and the like can be used, and specifically, mineral oil such as industrial lubricating oil containing saturated hydrocarbon (paraffin), higher alcohols such as stearyl alcohol, ester plasticizers such as dioctyl phthalate, and the like can be used. Among them, mineral oil is preferable in terms of easy reuse. The plasticizer is preferably added to a raw material composition mainly composed of a polyolefin resin, a fine silica powder and a plasticizer in an amount of 30 to 70 wt%.
As described above, the raw material composition mainly composed of the polyolefin resin, the fine silica powder and the plasticizer is melt-kneaded and molded into a film-like material having a predetermined shape, and then the plasticizer is removed to make the separator porous, whereby the content of the plasticizer in the separator made of the microporous film can be zero. However, the liquid separator for a lead-acid battery can contribute to improvement in oxidation resistance by containing an appropriate amount of a plasticizer such as mineral oil. In such a case, the content of the plasticizer in the separator is preferably 5 to 30% by weight. However, from the viewpoint that the porosity of the microporous film decreases and the electrical resistance of the microporous film separator deteriorates if the content of the plasticizer is increased, the content of the plasticizer is more preferably 20% by weight or less.
As the solvent for extracting and removing the plasticizer, a saturated hydrocarbon-based organic solvent such as hexane, heptane, octane, nonane, decane, or the like can be used.
If necessary, additives such as a surfactant (hydrophilizing agent), an antioxidant, an ultraviolet absorber, a weather resistant agent, a lubricant, an antibacterial agent, a fungicide, a pigment, a dye, a colorant, an antifogging agent, and a matting agent may be added (blended) to the raw material composition or the microporous film in such a range that the object and effect of the present invention are not impaired.
Even though the microporous film contains a large amount of the silica fine powder having a large specific surface area and high hydrophilicity, and thus has hydrophilicity, wettability to a sulfuric acid electrolyte solution of an aqueous solution liquid lead-acid battery, and permeability (impregnation property) of the sulfuric acid electrolyte solution, when the sulfuric acid electrolyte solution is injected into a laminate in which a plate and a separator are tightly assembled in a battery case, it is preferable to contain 0.2 to 8 wt% of a surfactant (solid component) in the microporous film in order to quickly absorb the electrolyte solution in the pores of the separator and quickly replace the pores of the separator with the electrolyte solution.
As a method for incorporating the surfactant in the microporous film, there are a method of adding the surfactant in a dispersed state in advance to a raw material composition before film formation (internal addition method) and a method of performing post-treatment (adhesion treatment) on the microporous film from which the plasticizer is removed after film formation (external addition method), and the method of adding the surfactant in advance to the raw material composition (internal addition method) is preferable from the viewpoint that the production process can be simplified and the surfactant can be made difficult to bleed out from the microporous film of the present invention. The content (necessary amount) of the surfactant (solid component) is 0.2 to 8 wt% in the microporous film. Even if the content of the surfactant (solid content) is increased to more than this range, the effect of improving the hydrophilicity of the microporous film is not greatly improved, but, on the contrary, the porosity of the microporous film is decreased, which leads to an increase in internal resistance (resistance) as a separator for a liquid lead-acid battery or an increase in self-discharge as a separator for a liquid lead-acid battery. Therefore, the content of the surfactant (solid content) is more preferably 0.2 to 5% by weight in the microporous film.
The surfactant may be any material that can improve the hydrophilicity of the microporous membrane, and any of nonionic surfactants, cationic surfactants, and anionic surfactants can be used. As the nonionic surfactant, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylallyl ethers, glycerin monofatty acid esters, sorbitan fatty acid esters, and the like can be used. As the cationic surfactant, aliphatic amine salts, quaternary ammonium salts, polyoxyethylene alkylamines, alkylamine oxides, and the like can be used. As the anionic surfactant, alkylsulfonates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, alkylsulfosuccinates, dodecylbenzenesulfonates, and the like can be used. Among them, alkylbenzenesulfonates, alkylsulfosuccinates, and dodecylbenzenesulfonates are preferable because they can impart high hydrophilicity to a polyolefin resin by adding a small amount of the resin, and can produce a microporous film (production by heating and melting molding) by adding a surfactant to a raw material composition in advance by imparting relatively high heat resistance to the polyolefin resin.
Examples
Next, examples of the present invention will be described in detail together with comparative examples.
(example 1)
An ultrahigh-molecular-weight polyethylene resin powder (melting point about 135 ℃ C.) having a weight-average molecular weight of 150 ten thousand as a polyolefin resin was prepared by mixing 1000 parts by weight of a synthetic amorphous silica prepared by a precipitation method and having a specific surface area of 200m by the BET method2(wherein the content of salts such as sodium sulfate generated as a by-product in the production process is reduced by increasing the flow rate of washing water more than conventional, and the mixing of Cl component is reduced by using washing water having a Cl component less than conventional, so that the microporous membrane (10 cm. times.10 cm. times.2 sheets) to be finally obtained is heated at a high temperatureThe concentration (ICP emission Spectroscopy) of alkali metal components (Li, Na, K, Rb, Cs) when the glass was immersed in 126g of sulfuric acid having a specific gravity of 1.26 at 50 ℃ for 24 hours was 5mg/100cm2Not more than one piece and the concentration (ICP emission spectrometry) of halogen components (F, Cl, Br, I) was 0.4mg/100cm2Hereinafter, 2590 parts by weight), 5380 parts by weight of paraffin mineral oil as a plasticizer, and 109 parts by weight of alkyl sulfosuccinate (solid content) as a surfactant were mixed in an レーディゲ mixer, the raw material mixture was extruded into a sheet shape while being heated, melted and kneaded using a twin-screw extruder having a T-die attached to the tip thereof, and the sheet was passed between a pair of molding rolls each having a predetermined groove engraved in one roll for a main rib for electrode plate contact, to obtain a film-like material in which the main rib for electrode plate contact having a predetermined shape was integrally molded on one surface of a flat sheet. Then, the film-like material was immersed in n-hexane to extract and remove a predetermined amount of paraffin mineral oil, and dried to obtain a ribbed microporous film having a base thickness of 0.20mm, a porosity of 62 vol% by mercury intrusion method, an average pore diameter of 0.09 μm by mercury intrusion method, and a maximum pore diameter of 0.65 μm by mercury intrusion method, the microporous film being composed of 22.9 wt% of a polyethylene resin, 59.3 wt% of fine silica powder, 16.0 wt% of paraffin mineral oil, and 1.8 wt% of a surfactant (solid content). This was used as a separator for a liquid lead-acid battery of example 1.
(example 2)
An ultrahigh-molecular-weight polyethylene resin powder (melting point about 135 ℃ C.) having a weight-average molecular weight of 150 ten thousand as a polyolefin resin was prepared by mixing 1000 parts by weight of a synthetic amorphous silica prepared by a precipitation method and having a specific surface area of 200m by the BET method2(wherein, the content of salts such as sodium sulfate generated as a by-product in the production process was further reduced by increasing the flow rate of the washing treatment water as compared with example 1, and the mixing of Cl component was reduced by using the washing treatment water having a Cl component smaller than that of the conventional one, so that the microporous membrane (10 cm. times.10 cm. times.2 sheets) finally obtained was immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ and left to stand for 24 hoursThe concentration of the alkali metal components (Li, Na, K, Rb, Cs) in (ICP emission spectroscopic analysis) was 4mg/100cm2Not more than one piece and the concentration (ICP emission spectrometry) of halogen components (F, Cl, Br, I) was 0.4mg/100cm2Hereinafter, 2590 parts by weight), 5380 parts by weight of paraffin mineral oil as a plasticizer, and 109 parts by weight of alkyl sulfosuccinate (solid content) as a surfactant were mixed in an レーディゲ mixer, the raw material mixture was extruded into a sheet shape while being heated, melted and kneaded using a twin-screw extruder having a T-die attached to the tip thereof, and the sheet was passed between a pair of molding rolls each having a predetermined groove engraved in one roll for a main rib for electrode plate contact, to obtain a film-like material in which the main rib for electrode plate contact having a predetermined shape was integrally molded on one surface of a flat sheet. Then, the film-like material was immersed in n-hexane to extract and remove a predetermined amount of paraffin mineral oil, and dried to obtain a ribbed microporous film having a base thickness of 0.20mm, a porosity of 62 vol% by mercury intrusion method, an average pore diameter of 0.09 μm by mercury intrusion method, and a maximum pore diameter of 0.65 μm by mercury intrusion method, the microporous film being composed of 22.9 wt% of a polyethylene resin, 59.3 wt% of fine silica powder, 16.0 wt% of paraffin mineral oil, and 1.8 wt% of a surfactant (solid content). This was used as a separator for a liquid lead-acid battery of example 2.
(example 3)
An ultrahigh-molecular-weight polyethylene resin powder (melting point about 135 ℃ C.) having a weight-average molecular weight of 150 ten thousand as a polyolefin resin was prepared by mixing 1000 parts by weight of a synthetic amorphous silica prepared by a precipitation method and having a specific surface area of 200m by the BET method2(wherein the content of salts such as sodium sulfate produced as a by-product in the production process was reduced by increasing the flow rate of the washing water more than conventional, and the mixing of Cl component was further reduced by using the washing water having a Cl component smaller than that in example 1, so that the finally obtained microporous membrane (10 cm. times.10 cm. times.2 sheets) was immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ for 24 hours to obtain a concentration (ICP emission) of alkali metal components (Li, Na, K, Rb, Cs)Optical spectroscopic analysis) to 5mg/100cm2Not more than one piece and the concentration (ICP emission spectrometry) of halogen components (F, Cl, Br, I) was 0.1mg/100cm2Hereinafter, 2590 parts by weight), 5380 parts by weight of paraffin mineral oil as a plasticizer, and 109 parts by weight of alkyl sulfosuccinate (solid content) as a surfactant were mixed in an レーディゲ mixer, the raw material mixture was extruded into a sheet shape while being heated, melted and kneaded using a twin-screw extruder having a T-die attached to the tip thereof, and the sheet was passed between a pair of molding rolls each having a predetermined groove engraved in one roll for a main rib for electrode plate contact, to obtain a film-like material in which the main rib for electrode plate contact having a predetermined shape was integrally molded on one surface of a flat sheet. Then, the film-like material was immersed in n-hexane to extract and remove a predetermined amount of paraffin mineral oil, and dried to obtain a ribbed microporous film having a base thickness of 0.20mm, a porosity of 62 vol% by mercury intrusion method, an average pore diameter of 0.09 μm by mercury intrusion method, and a maximum pore diameter of 0.65 μm by mercury intrusion method, the microporous film being composed of 22.9 wt% of a polyethylene resin, 59.3 wt% of fine silica powder, 16.0 wt% of paraffin mineral oil, and 1.8 wt% of a surfactant (solid content). This was used as a separator for a liquid lead-acid battery of example 3.
Comparative example 1
An ultrahigh-molecular-weight polyethylene resin powder (melting point about 135 ℃ C.) having a weight-average molecular weight of 150 ten thousand as a polyolefin resin was prepared by mixing 1000 parts by weight of a synthetic amorphous silica prepared by a precipitation method and having a specific surface area of 200m by the BET method2(wherein, in the case of conventional washing treatment water in which the content of salts such as sodium sulfate produced as by-products in the production process is as conventional and Cl component is used as conventional, the mixing of Cl component is not reduced, and the concentration of alkali metal component (ICP emission spectroscopy) when the finally obtained microporous membrane (10 cm. times.10 cm. times.2 sheets) is immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ and left to stand for 24 hours exceeds 5mg/100cm2Per sheet and the concentration of halogen component (ICP emission spectroscopic analysis) exceeds 0.4mg/100cm22590 parts by weight), 5380 parts by weight of paraffin mineral oil as a plasticizer, and 109 parts by weight of alkyl sulfosuccinate (solid content) as a surfactant were mixed in an レーディゲ mixer, the raw material mixture was extruded into a sheet form while being heated, melted and kneaded using a twin-screw extruder having a T-die attached to the tip thereof, and the sheet was passed between a pair of molding rolls each having a predetermined groove for a main rib for electrode plate contact engraved in one roll thereof, to obtain a film-like material in which the main rib for electrode plate contact having a predetermined shape was integrally molded on one surface of a flat sheet. Then, the film-like material was immersed in n-hexane to extract and remove a predetermined amount of paraffin mineral oil, and dried to obtain a ribbed microporous film having a base thickness of 0.20mm, a porosity of 62 vol% by mercury intrusion method, an average pore diameter of 0.09 μm by mercury intrusion method, and a maximum pore diameter of 0.65 μm by mercury intrusion method, the microporous film being composed of 22.9 wt% of a polyethylene resin, 59.3 wt% of fine silica powder, 16.0 wt% of paraffin mineral oil, and 1.8 wt% of a surfactant (solid content). This was used as a separator for a liquid lead-acid battery of comparative example 1.
Comparative example 2
The specific surface area of the synthetic amorphous silica produced by the sedimentation method and obtained by the BET method was 200m2(wherein the content of salts such as sodium sulfate produced as a by-product in the production process is as conventional, but the Cl component is less than that in the conventional washing treatment water, thereby reducing the mixing of the Cl component, and the concentration of alkali metal component (ICP emission spectroscopy) exceeds 5mg/100cm when the finally obtained microporous membrane (10 cm. times.10 cm. times.2 sheets) is immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ and left for 24 hours2Perhaps and the concentration of the halogen component (ICP emission Spectroscopy) was 0.4mg/100cm2Not more than one piece), except that in the same manner as in comparative example 1, a polyethylene resin composition having a base thickness of 0.20mm and comprising 22.9 wt% of a polyethylene resin, 59.3 wt% of fine silica powder, 16.0 wt% of a paraffin-based mineral oil, and 1.8 wt% of a surfactant (solid content) was obtainedA ribbed microporous film having a porosity of 62% by volume by mercury intrusion, an average pore diameter of 0.09 μm by mercury intrusion, and a maximum pore diameter of 0.65 μm by mercury intrusion. This was used as a separator for a liquid lead-acid battery of comparative example 2.
Comparative example 3
The specific surface area of the synthetic amorphous silica produced by the sedimentation method and obtained by the BET method was 200m2(wherein, when the content of salts such as sodium sulfate generated as a by-product in the production process is reduced by increasing the flow rate of the washing water more than the conventional one, but the Cl component is used as the conventional washing water, the mixing of the Cl component is not reduced, and the concentration of the alkali metal component (ICP emission spectroscopy) when the finally obtained microporous membrane (10 cm. times.10 cm. times.2 sheets) is immersed in 126g of sulfuric acid having a specific gravity of 1.26 at a temperature of 50 ℃ and left for 24 hours is 5mg/100cm2Less than one sheet and the concentration of halogen component (ICP emission spectroscopic analysis) exceeds 0.4mg/100cm2Except for this, in the same manner as in comparative example 1, a ribbed microporous film having a base thickness of 0.20mm, a porosity of 62 vol% by mercury intrusion method, an average pore diameter of 0.09 μm by mercury intrusion method, and a maximum pore diameter of 0.65 μm by mercury intrusion method was obtained, the microporous film being composed of 22.9 wt% of a polyethylene resin, 59.3 wt% of fine silica powder, 16.0 wt% of a paraffin-based mineral oil, and 1.8 wt% of a surfactant (solid content). This was used as a separator for a liquid lead-acid battery of comparative example 3.
Next, various characteristics of the separators of examples 1 to 3 and comparative examples 1 to 3 obtained as described above were evaluated by the following methods. The results are shown in table 1. The MD (MD direction) refers to the direction in which the produced sheet is produced, and the CD (CD direction) refers to the direction perpendicular to the MD direction.
Foundation thickness
The microporous film (when having rib-like protrusions, the rib-like protrusions were not included) was measured at any point or at a plurality of points using a dial gauge (ピーコック G-6, Kawasaki corporation).
Tensile Strength, elongation >
Rectangular dimensions of 10mm × 70mm were cut out from the microporous film in the MD and CD directions to obtain test pieces. Using a Shopper type of capacity 294N or less or a tensile tester based thereon, a specimen was mounted with a holding interval (a) of the tester of about 50mm, a tensile test was performed at a tensile rate of 200mm per minute, and a tensile load (b) and a distance (c) at the time of breakage of the specimen were read. The tensile strength was calculated by dividing the tensile load (b) by the cross-sectional area of the sample piece. The elongation is calculated by dividing the distance (c) by the holding interval (a) of the tester.
Porosity
The pore volume (mercury intrusion method) and the true density (immersion method) of the microporous film were calculated from the following equation.
Porosity ═ Vp/((1/ρ) + Vp)
Wherein, Vp: pore volume (cm)3/g), ρ: true density (g/cm)3)
Average pore diameter
The pore diameter distribution was calculated from the pressure at the time of mercury intrusion and the mercury capacity. The pore diameter at the time when 50% of the total pore volume of mercury was pushed in was defined as the average pore diameter (median diameter).
Maximum aperture
From the pore diameter distribution curve in the average pore diameter test, the pore diameter at which mercury penetration was started was defined as the maximum pore diameter.
Permeability
A test piece obtained by cutting a microporous film into a square size of 70mm × 70mm was floated on the surface of sulfuric acid having a specific gravity of 1.20 at a temperature of 20 ℃, and then the time taken until a part of the test piece was discolored was measured to determine the permeability (sec).
Resistance
The microporous film was cut into a square size of 70mm × 70mm to prepare a sample piece, and the measurement was performed using a test apparatus according to SBA S0402.
Oxidation resistance life
A positive electrode and a negative electrode made of a 50mm × 50mm square lead plate were laminated in a concentric manner with the square direction aligned by sandwiching a separator made of a microporous film cut into a 70mm × 70mm square shape, an electrode group composed of the laminated positive electrode (1 sheet), separator (1 sheet), and negative electrode (1 sheet) was pressurized at 19.6kPa and assembled in a battery cell, 1000ml of a dilute sulfuric acid electrolyte having a specific gravity of 1.300(20 ℃) was injected, a direct current of 5.0A was passed at a liquid temperature of 50 ± 2 ℃, and the energization time at the time when the terminal voltage became 2.6V or less or the voltage became 0.2V or more was measured and defined as an oxidation-resistant time (h). Table 1 shows relative values when the value of comparative example 1 is 100.
Dendrite short circuit characteristics
A microporous film cut into a square of 70mm X70 mm was held by 2 lead plates (made of pure lead and having a thickness of 3mm) of a square of 50mm X50 mm so that the microporous film was aligned with the center of the 3 squares of the 2 lead plates and the sides of the 3 squares were parallel to each other, set in a horizontal state in a battery container, and a weight (weight り) of 5kg was placed thereon (at the center of the square), and then a saturated aqueous solution of lead sulfate was injected. Thereafter, a current of 3.2mA was applied to the lead plate, and the change in voltage was continuously recorded. The voltage slightly rises after the start of energization, and then slowly falls. The time until the voltage dropped to 70% of the maximum voltage at that time was measured. Table 1 shows relative values when the value of comparative example 1 is 100.
ICP emission spectrometer
2 pieces of the microporous membrane cut into a square of 100mm × 100mm were placed in a beaker containing 126g of sulfuric acid having a specific gravity of 1.26. The mixture was placed in a constant temperature water bath maintained at 50 ℃ and allowed to stand for 24 hours. After 24 hours of standing, the microporous membrane was taken out from the sulfuric acid (extract). The sulfuric acid (extract solution) was diluted to 1/10, and the alkali metal components (Li, Na, K, Rb, Cs) and halogen components (F, Cl, Br, I) in the diluted solution were quantitatively analyzed by an ICP emission spectrophotometer. The obtained value was converted from ppm to mg/100cm2One sheet (every 1 sheet)The product is 100cm2The weight of the microporous film of (1) (wherein the base thickness of each microporous film is defined as 0.2mm, and when the base thickness is different from the above, the value is converted and corrected so as to be 0.2 mm).
Battery test (charge acceptance, battery life)
In terms of charge acceptance, the charge current after the start of charging when discharged at a current rate of 5 hours for 2.5 hours was measured in accordance with JIS D5301 (2006). In terms of battery life, a charge/discharge cycle test was performed by a method of a light load life test according to JIS D5301 (2006), and the number of cycles was measured when the voltage at 30 seconds became 7.2V or less. The charge acceptance and the battery life in table 1 are relative values (relative results) when the value of comparative example 1 is 100.
[ Table 1]
The results in Table 1 show the following.
(1) In the separator of example 1 of the present invention, the concentration of the alkali metal component (ICP emission spectroscopic analysis) was adjusted to 5mg/100cm2The charge acceptance was improved by adjusting the concentration of the halogen component (ICP emission Spectroscopy) to 0.4mg/100cm2And/or less, thereby preventing the corrosion of plate grids and polar columns and improving the service life of the battery.
(2) The separator of example 2 of the present invention was further adjusted to have a concentration of an alkali metal component (ICP emission Spectroscopy) of 4mg/100cm with respect to the separator of example 12And/or less, thereby further improving the charge acceptance.
(3) The separator of example 3 of the present invention was further analyzed by adjusting the concentration of the halogen component (ICP emission spectroscopy) to 0.1mg/100cm with respect to the separator of example 12And/or less, so that the battery life is further improved.
(4) Therefore, it is considered that if the separators of examples 1 to 3 of the present invention are applied to lead-acid batteries for automobiles, the separators contribute to improvement in charge acceptance and battery life required for idling stop vehicles.
(5) In the separator of comparative example 1, the concentration of the alkali metal component (ICP emission spectroscopic analysis) exceeded 5mg/100cm2Perhaps, the charge acceptance was 100%, and no improvement was observed, and the concentration of the halogen component (ICP emission spectroscopic analysis) exceeded 0.4mg/100cm2Therefore, corrosion of the plate grid and the electrode terminal was promoted, and the battery life was 100%, and no improvement was observed.
(6) The separator of comparative example 2 was analyzed by making the concentration of the halogen component (ICP emission spectroscopy) 0.4mg/100cm2Less than one piece, thereby preventing the corrosion of plate grid and pole and improving the service life of the battery, but the concentration of alkali metal component (ICP emission spectroanalysis) exceeds 5mg/100cm2Charge acceptance was therefore 100%, and no improvement was seen.
(7) The separator of comparative example 3 was prepared by adjusting the concentration of the alkali metal component (ICP emission Spectroscopy) to 5mg/100cm2The charge acceptance was improved by a sheet of the halogen-containing compound having a concentration of 0.4mg/100cm or less (ICP emission spectroscopic analysis)2Therefore, corrosion of the plate grid and the electrode terminal was promoted, and the battery life was 100%, and no improvement was observed.
Claims (4)
1. A separator for a liquid lead-acid battery, comprising a microporous membrane containing 40% by weight or more of a fine silica powder, which is a synthetic amorphous silica produced by the following sedimentation method: reacting an aqueous alkali silicate solution with an inorganic acid to precipitate synthetic amorphous silica, and then adjusting the purity by filtration and washing; characterized in that the concentration of alkali metal component in 24 hours after immersing 10cm × 10cm × 2 pieces of the microporous membrane in 126g of sulfuric acid having a specific gravity of 1.26 at 50 ℃ is 5mg/100cm based on ICP emission spectroscopy2Less than or equal to 0 sheet based on the base thickness of the microporous membrane2 mm-converted value, and the concentration of the halogen component based on ICP emission spectroscopic analysis was 0.4mg/100cm2The microporous membrane has a base thickness of 0.2 to 0.3mm, calculated as 0.2mm of the base thickness of the microporous membrane.
2. The separator for a liquid lead-acid battery according to claim 1, wherein said filtering and washing are carried out using ion-exchanged water or groundwater containing no salt, i.e., sodium chloride.
3. The separator for a liquid lead-acid battery according to claim 1 or 2, wherein the microporous film is a microporous film mainly composed of the fine silica powder and a polyolefin resin.
4. The separator for a liquid lead-acid battery according to claim 3, wherein the microporous film has an average pore diameter of 0.01 to 0.5 μm by mercury intrusion method and a porosity of 50 to 90 vol% by mercury intrusion method.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
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| JP2016072387 | 2016-03-31 | ||
| JP2016-072387 | 2016-03-31 | ||
| PCT/JP2017/013500 WO2017170977A1 (en) | 2016-03-31 | 2017-03-31 | Separator for liquid-type lead storage battery |
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| CN108886124A CN108886124A (en) | 2018-11-23 |
| CN108886124B true CN108886124B (en) | 2021-06-04 |
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| JP (2) | JP7248425B2 (en) |
| CN (1) | CN108886124B (en) |
| WO (1) | WO2017170977A1 (en) |
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| Publication number | Publication date |
|---|---|
| JP2022100369A (en) | 2022-07-05 |
| WO2017170977A1 (en) | 2017-10-05 |
| CN108886124A (en) | 2018-11-23 |
| JP7248425B2 (en) | 2023-03-29 |
| JPWO2017170977A1 (en) | 2019-02-07 |
| JP7444920B2 (en) | 2024-03-06 |
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Effective date of registration: 20220810 Address after: Gifu County, Japan Patentee after: ENTEC Asia Co.,Ltd. Address before: Tokyo Patentee before: Nippon Sheet Glass Co.,Ltd. |